Medical diagnostic imaging and scanner systems such as magnetic resonance imaging (MRI) apparatus, X-ray machines, positron emission tomography (PET) scanners, and computer tomography (CT) scanners are well known. Such machines are quite popular as a tool for providing images of internal portions of patients for diagnosis of medical conditions, such as internal injuries, cancerous tumors and the like. Owing to good quality tomographic images with low dosage X-ray radiation, the CT scanner has become especially well accepted by the medical profession for examining patients and diagnosing medical conditions.
An annular gantry normally supports many of the components of a CT scanner and includes an outer ring secured to a stand and an inner ring mounted for rotation within the outer ring. During a scanning procedure, a pallet of a patient table is extended through the center of the gantry and the inner ring is rotated about the pallet. A patient lies on the pallet within the center of the gantry during the scanning procedure. The components supported by the gantry can include an x-ray tube for providing the x-ray beam, one or more high voltage power supplies, balancing weights, a data acquisition module, and a bank of detectors diametrically opposed from the x-ray source. At least some of these components are secured in the inner ring for rotation therewith.
In order to obtain tomographic images of a patient with a CT scanner or X-ray CT apparatus, it is necessary that the patient be located exactly at a predetermined position inside the opening of an annular scan gantry of the apparatus. For this reason, such apparatus has been provided with a patient handling couch or table which is moveable vertically to be in line with an axis of rotation of the scan gantry, and then moveable horizontally, or axially in and out of the scan gantry parallel with the axis of rotation.
Several patient tables are known for this purpose. For example, U.S. patents showing various patient tables include: U.S. Pat. Nos. 4,131,802; 4,567,894; 4,568,071; 4,576,368; 4,613,122; 4,727,328; 4,914,682; 4,984,774; 5,058,871; 5,066,915; 5,199,123; 5,204,629; 5,273,043; 5,657,498; and 5,960,054. Many of these patents show patient tables having horizontally extendable patient pallets.
What is still desired, however, is a new and improved patient table for use with medical diagnostic imaging and scanner systems. In particular, what is desired a patient table having an improved horizontal drive apparatus for horizontally moving a pallet of the patient table. Among other features and advantages, the new and improved horizontal drive apparatus will preferably be a simple, yet reliable and robust design, and will relatively smoothly extend and retract the pallet such that a patient lying on the pallet can be correctly positioned in a scanning machine in a comfortable manner.
A patient table including the horizontal drive apparatus of the present invention will preferably also be provided with new and improved structural members. Among other features and advantages, the new and improved structural members will greatly simplify the design, the assembly and the overall cost of the patient table.
In addition, a patient table including the horizontal drive apparatus of the present invention will preferably be provided with a new and improved sensor assembly for providing an indication of the horizontal position of the pallet during operation of the horizontal drive apparatus. Among other features and advantages, the new and improved sensor assembly will provide extremely accurate and consistent horizontal position measurements.
Preferably, a patient table including the horizontal drive apparatus of the present invention will also be provided with a new and improved bearing assembly for supporting the pallet. Among other features and advantages, the new and improved bearing assembly will allow the pallet to be easily and quickly centered on the patient table.